The Effects of Psilocybin on Social Connectedness

The study is a randomized, double-blind, placebo-controlled, expectancy-controlled, mechanistic trial. This study looks to explore whether a single dose of psilocybin (25mg) reduces amygdala reactivity to negative socioemotional stimuli during the Facial Emotion Recognition Task (FERT) compared to a placebo in adults who feel lonely or those with unresolved grief symptoms. The main purpose of this study is to determine whether psilocybin engages validated neural and behavioral targets associated with social information processing (SIP), specifically, amygdala threat reactivity, dorsal anterior cingulate, and insula activity during social rejection, and whether this early neural "target engagement" predicts downstream improvements in loneliness and social connectedness. By establishing these mechanistic links, this research aims to provide a data driven, experimental medicine foundation for developing effective, mechanism-based interventions to reduce loneliness.